Switching Last and First names of artists and composers

I have a bunch of files in which artists and composers' names are tagged as "Last, First" and I want to re-tag them as "First Last". What's the fastest way to swith the names of in their respective fields?

For example, I currently have

Artist: Marriner, Neville
Composer: Mozart, Wolfgang Amadeus

and I want to convert them to

Artist: Neville Marriner
Composer: Wolfgang Amadeus Mozart

Surely somebody's worked through this problem before. If it's a FAQ, I couldn't find it but would appreciate a pointer.

Thanks in advance,

 - Rich

This can be done via an action Replace with regular expression

Field: ARTIST
Regular expression: (.+), (.+)
Replace matches with: $2 $1

Thank you! That worked perfectly--exactly as I wanted.

 - Rich